WhatsApp transfer

I tried to transfer WhatsApp from my old iPhone 4 to my new iPhone SE. The chat history last backed up on iCloud on 9th February, which is when I started setting up the new phone.

I didn't know, until it was too late that WhatsApp would not back up on the old phone after I had checked in to iCloud on the new one! Pity they don't warn you about that in advance.

I figured that the new phone could at least be updated to 9th February, and since nothing else worked, I migrated the WhatsApp account to the new phone.

The result was that it disappeared entirely from the old one, and on the new one it says there is no backup and nothing to restore. I seem to have inadvertently deleted years of WhatsApp chats with lots of important people, and I am devastated.

Is there any way I can import the old WhatsApp account from iCloud?